Method and apparatus for detecting object

ABSTRACT

A method and apparatus for detecting an object on a road around a vehicle. The method includes referring to three-dimensional geographical data, calculating a distance D A  to a detecting object BLD in a 360 degree range, defining an area for the detecting target by the distance D A , measuring a distance D B  to the object BLD and an object OBL in the 360 degree range when the vehicle travels, determining that the object is present on a road around the vehicle when D B &lt;D A , and outputting the determination result.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to methods and apparatuses fordetecting objects around vehicles, and more specifically, to a methodand apparatus that are capable of accurately detecting an obstruction ona road.

[0003] 2. Description of the Related Art

[0004] A radar device mounted in a vehicle, such as a millimeter-waveradar device, may be used to detect a preceding vehicle. This functionmay be utilized for speed control using an accelerator or a break tokeep a space between vehicles in fields of an anti-lock brake system(ABS) and cruise-control techniques, and also used for steering control.Locations where such a radar device is utilized include straight roadssuch as freeways, on which vehicles can travel at high speed. Such radardevices are designed so that its receiving sensitivity can detectvehicles traveling ahead in the same direction and oncoming in theopposite direction and obstacles at sides of roads, such as guardrails,and signs.

[0005] Japanese Unexamined Patent Application Publication No. 10-221451discloses a manner of determining whether an object ,such as a precedingvehicle or a roadside structure, detected by a vehicle-mounted radardevice is an obstruction. Specifically, a relative location of an objectwith reference to a vehicle is calculated on the basis of signalssupplied by a vehicle-mounted radar device, an absolute location of theobject based on the relative location and a current position of thevehicle is found, the absolute location is compared to location data ona roadside structure, and thereby the object is thereby determined to beor not be a roadside structure.

[0006] The vehicle-mounted radar devices, such as millimeter-wave radarhave a fixed receiving sensitivity. Therefore, when the receivingsensitivity is set at a rather high level (a threshold of strength ofreceived radio waves for detecting an object is set at a rather lowlevel), as illustrated in FIG. 11A, preceding vehicles 1 and 2, a sign3, and guardrails (not shown) can be detected and displayed on a radarscreen. On the other hand, when the receiving sensitivity of thevehicle-mounted radar device is set at a rather low level, as shown inFIG. 11B, the preceding vehicles 1 and 2 can be detected, but the sign 3and the guardrails cannot be detected. Accordingly, the receivingsensitivity of the vehicle-mounted radar device is set at a level ofFIG. 11A that is sufficient for detecting the sign 3 and the guardrails.

[0007] However, detecting conditions vary with surroundings; forexample, as shown in FIG. 11C, when a vehicle travels on a section of aroad with sound barriers, a walled-in area, such as tunnels, and a placeenclosed with a steel material, such as bridges, increased radio wavesreflected from the wall are picked up and output on a radar screen asnoise (circles 4 on the radar screen). As a result, the detection ofnearby vehicles becomes difficult.

[0008] The device of Japanese Unexamined Patent Application No.10-221451 requires distinguishing whether a detected object is ascanning target (another vehicle) or an object not to be scanned (aroadside structure), and it is necessary to compare an absolute locationwith location data on the roadside structure. This comparison operationplaces a heavy load on the radar device, resulting in a problem in whichobstructions traveling at high speed cannot be detected.

SUMMARY OF THE INVENTION

[0009] Accordingly, it is an object of the present invention to detect atarget (e.g. another vehicle) accurately even when detecting conditionsvary with surroundings, such as tunnels, bridges, and sound barriers.

[0010] Another object of the present invention is to detect a scanningtarget without distinguishing between a scanning target (e.g. anothervehicle) and an object not to be scanned (a roadside structure).

[0011] A further object of the present invention is to detect a scanningtarget on the basis of comparison of distances.

[0012] According to a first aspect, geographical data is referred to; itis monitored whether a vehicle reaches a point to change a sensitivityof detecting an object of a radar device; the sensitivity is changedwhen the vehicle reaches the point to change the sensitivity; it ismonitored whether the vehicle reaches a point to reset the sensitivity;the sensitivity is reset to its original level when the vehicle reachesthe point to reset the sensitivity. Therefore, a target can beaccurately detected, even when detecting conditions vary withsurroundings, such as a tunnel, or a bridge.

[0013] According to a second aspect of the present invention,three-dimensional (3-D) geographical data is referred to; a distanceD_(A) between a position of a vehicle and a detecting target in therange of 360 degrees; and an area for the detecting target is defined bythe distance D_(A); a distance D_(B) to an object is measured in therange of 360 degrees; it is determined that the object (e.g. anothervehicle) is present on a road around the vehicle when a locationcorresponding to the distance D_(B) lies in the area for the detectingtarget, i.e., D_(B)<D_(A); and the determination result is outputted.Therefore, a scanning target can be detected without distinguishingbetween a scanning target (e.g. another vehicle) and an object not to bescanned (a roadside structure), and the scanning target can be detectedonly by comparison of distances.

[0014] Additionally, since scanning is performed on solely an area whereanother vehicle can be present, unnecessary scanning operations areeliminated (effective scanning is achieved).

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a schematic illustration of a first embodiment of thepresent invention;

[0016]FIGS. 2A and 2B are illustrations showing radar screens accordingto receiving sensitivities;

[0017]FIG. 3 is a block diagram of the first embodiment;

[0018]FIG. 4 is a flowchart of processing of controlling the sensitivityof the radar device of the first embodiment;

[0019]FIGS. 5A to 5C are schematic illustrations of a second embodiment;

[0020]FIG. 6 is a block diagram of the second embodiment;

[0021]FIGS. 7A to 7C are illustrations of radar device scanning areas;

[0022]FIG. 8 is a flowchart of processing of detecting an obstruction ofthe second embodiment;

[0023]FIG. 9 is a flowchart of processing of defining an area for adetecting target;

[0024]FIGS. 10A and 10B are illustrations explaining the processing ofdefining the area for the detecting target; and

[0025]FIGS. 11A to 11C are illustrations explaining radar screens of aknown radar device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS (A) First Embodiment

[0026]FIG. 1 is a schematic illustration of a first embodiment. When avehicle 11 refers to geographic data and reaches a point to change asensitivity of detecting an object of a radar device 12, for example, itreaches an entrance ENT of a tunnel 13, the sensitivity of the radardevice 12 is reduced. This results in decreased detectable noise insidethe tunnel and thus facilitates detecting another vehicle to be actuallydetected. When the vehicle 11 reaches a point to reset the sensitivityof detecting the object of the radar device 12, for example, it reachesan exit EXT of the tunnel 13, the sensitivity is reset to its originallevel. Therefore, signs and guardrails, in addition to other vehicles,can be detected. The points to change/reset the sensitivity of detectingthe object may be an entrance/exit of a tunnel, as mentioned above, ormay be a beginning/end of a section of a road with sound barriers orthose of a steel bridge, where increased noise would be picked up.

[0027]FIG. 2A shows a radar screen when the vehicle travels on a generalroad with a receiving sensitivity being set at a rather high level,displaying detected vehicles 21 and 22 and a detected sign 23. FIG. 2Bshows a radar screen when the vehicle travels inside the tunnel with thereceiving sensitivity being set at a rather low level. In this case,detected noises 24 are far less than that shown in FIG. 1C, andtherefore, detecting the vehicles 21 and 22 is made easier.

[0028]FIG. 3 is a block diagram of the first embodiment.

[0029] A vehicle positioning device 51 measures a position of thevehicle by means of, for example, a global positioning system (GPS). Ageographical database 52 contains geographical data includinginformation about identifiable points to decrease a sensitivity andreset it on individual roads, in addition to general geographicalinformation. The vehicle positioning device 51 and the geographicaldatabase 52 may support a navigation system.

[0030] An obstruction detecting and controlling device 53 controls aradar device 56, acquires a distance and a direction to an obstruction,generates data for controlling display and/or audio message data,displays the data on a monitor 54 and/or raises an audio alarm byinputting the data to an alarm device 55. The obstruction detecting andcontrolling device 53 controls a sensitivity of the radar device 56following a flowchart shown in FIG. 4.

[0031] The radar device 56 emits a radio beam according to instructionsfrom the obstruction detecting and controlling device 53, scans in adirection of the beam over a range of −θ to +θ, receives radio wavesreflected from an object, detects a distance to the object and speedthereof in the range of −θ to +θ, and inputs the detected results to theobstruction detecting and controlling device 53.

[0032] The radar device 56 may use, for example, a vehicle-mountedmillimeter-wave radar module under a frequency modulated continuous wave(FMCW) system. The radar device 56 has: a radar controller 61 includinga driving circuit 61 a and a signal processing unit 61 b; a transmittingand receiving circuit 62 including a radio beam emitting unit 62 a foremitting a radio beam in response to a driving signal from the drivingcircuit 61a and a reflected radio-wave receiving unit 62 b for receivingthe radio waves reflected from the object; and a beam-scanning antenna63 for beam-scanning over the range of −θ to +θ. The signal processingunit 61 b switches between threshold levels of strength of radio wavesfor detecting an object in accordance with a sensitivity indicated bythe obstruction detecting and controlling device 53. On the basis ofreflected radio-wave signals greater than or equal to the threshold, itthen computes a distance and a direction to the object, and speedthereof, and inputs the results to the obstruction detecting andcontrolling device 53.

[0033]FIG. 4 is a flowchart showing a sensitivity switching performed bythe obstruction detecting and controlling device 53.

[0034] The obstruction detecting and controlling device 53 acquires aposition of the vehicle from the vehicle positioning device 51 (act101), refers to geographical data, and determines whether the vehiclehas reached a point to decrease a radar sensitivity (act 102). If not,processing repeats acts 101 and 102. If the vehicle has reached thepoint, the obstruction detecting and controlling device 53 provides theradar device 56 with instructions SCD for decreasing the sensitivity(act 103). The radar device 56 thus sets a threshold of strength ofreflected radio waves for detecting an object at a higher level, thusthe sensitivity is set at a rather low level.

[0035] The obstruction detecting and controlling device 53 acquires aposition of the vehicle from the vehicle positioning device 51 whiledetecting an object under the low-level sensitivity (act 104), refers tothe geographical data, and determines whether the vehicle has reached apoint to reset the radar sensitivity to its original level (act 105). Ifnot, the processing repeats acts 104 and 105. If the vehicle has reachedthe point, the obstruction detecting and controlling device 53 providesthe radar device 56 with instructions for resetting the sensitivity toits original level (act 106). The radar device 56 thus sets thethreshold of strength of reflected radio waves for detecting an objectat a lower level, thus the sensitivity is set at a rather high level,and detecting objects continues under the reset sensitivity.

(B) Second Embodiment

[0036]FIGS. 5A to 5C are schematic illustrations of a second embodiment.

[0037] An obstruction detecting and controlling device (not shown) of avehicle CAR refers to 3-D geographical data and calculates a distanceD_(A) from a position of the vehicle CAR to a detecting target (aroadside building) BLD in the range of 360 degrees (see FIG. 5A), anddefines an area for a detecting target by the distance D_(A). When thevehicle travels, a distance D_(B) to each of the object (BLD) and anobject (OBL) is measured in times or distances of predetermined length,as shown in FIGS. 5B and 5C. If a location corresponding to the distanceD_(B) lies in the area for the detecting target, i.e., D_(B)<D_(A), itis determined that the object is present on a road around the vehicle,and the determination result is output.

[0038] According to a first aspect, a scanning target can be detectedwithout distinguishing between a scanning target OBL (e.g. anothervehicle) and an object not to be scanned BLD (a roadside structure), andthe scanning target can be detected solely by comparison of distances.

[0039]FIG. 6 is a block diagram of the second embodiment; in thisFigure, the same reference numerals have been used as in the firstembodiment (FIG. 3) for the same parts. A first difference is that thegeographical database 52 has been replaced with a 3-D geographicaldatabase 52′ containing 3-D geographical data. This 3-D geographicaldata includes plan configurations of roads, sidewalks, buildings, andthe like and height information thereof, and can be used for displayinga 3-D map. A second difference is that the radar device 56 scans in therange of 360 degrees and a distance and speed can be detected.

[0040]FIGS. 7A to 7C are illustrations explaining radar devices that canscan in 360 degrees: FIG. 7A shows a radar device comprising a pluralityof radar device units, each of which has an α scanning area, for360-degree scanning; and FIG. 7B shows a radar device comprising a radardevice unit with an a scanning area that can rotate by a rotationmechanism for 360-degree scanning. As shown in FIG. 7C, in the radardevice unit with an α scanning area, an α (−10° to +10° in the Figure)in front of the vehicle 11 is a scanning area (sensing area) and anappropriate sensitivity achieves detecting the vehicles 21 and 22.

[0041]FIG. 8 is a flowchart of processing of detecting an obstruction ofthe second embodiment.

[0042] The obstruction detecting and controlling device 53 refers to 3-Dgeographical data and calculates a distance between a position of thevehicle and a roadside building in the range of 360 degrees, therebydefining an area for a detecting target before radar scanning (act 201).

[0043]FIG. 9 is a flowchart of detailed processing of act 201. FIGS. 10Aand 10B are illustrations explaining the processing of defining the areafor the detecting target.

[0044] Referring to FIG. 9, in the processing of defining the area forthe detecting target, the obstruction detecting and controlling device53 acquires 3-D geographical data around the position of the vehiclefrom the 3-D geographical database 52′ (act 201 a) and sets an initialdirection (act 201 b). Then, it determines whether an object (abuilding) greater than or equal to a predetermined height h0 is presentin the set direction (201 c). The height h0 is a reference height thatvehicles cannot pass over in terms of physical size, and is, forexample, 50 centimeters.

[0045] With respect to a direction in which the object greater than orequal to the reference height h0 is present, it is determined that anobject not to be scanned (e.g. building) is present in the direction; adistance D_(A) to the object is recorded associated with its direction(act 201 d). On the other hand, with respect to a direction in which theobject greater than or equal to the reference height h0 is not present,an effective distance of the radar device is recorded as a distanceD_(A) associated with its direction (act 201 e). In view of sidewalks, adistance D_(A) is recorded after the width of a sidewalk is subtractedfrom it.

[0046] Then, it is determined whether a distance D_(A) has been measuredin all directions (act 201 f); if not, a set direction is rotated apredetermined angle (act 201 g) and processing of act 201 c andsubsequent acts is repeated.

[0047] According to the processing of defining the area for thedetecting target, when buildings greater than or equal to the referenceheight h0 are present, which are hatched in FIG. 10A, the area for thedetecting target is the area hatched in FIG. 10B. In FIG. 10B, an areawithin a reference distance (an area within 5 meters in consideration ofsidewalks), which is the area where another vehicle cannot be present interms of physical size, is excluded from the area for the detectingtarget. This is because the distance required for another vehicle lyingin between the vehicle CAR and a building is 5 meters or more,considering sidewalks. However, this exclusion is optional.

[0048] Referring back to FIG. 8, when the processing of defining thearea for the detecting target is completed, the obstruction detectingand controlling device 53 determines that a direction satisfying that adistance D_(A) to an object not to be scanned is a predetermineddistance (5 meters in consideration of sidewalks) or greater is ascanning direction (act 202). Since it is determined that a direction ofD_(A)<5 m is not a scanning direction, no subsequent processing isperformed in the direction.

[0049] Then, the obstruction detecting and controlling device 53provides instructions for scanning (act 203), acquires a measureddistance D_(B) to an object in a scanning direction by the radar device56 (act 204), and compares the distance D_(A) to a roadside building inthe scanning direction with the measured distance D_(B) (act 205).

[0050] If D_(A)>D_(B), the object is an obstruction, such as anothervehicle, present on the road; the obstruction detecting and controllingdevice 53 displays it on the monitor 54. If the obstruction is tooclose, the alarm device 55 raises an audio alarm (act 206).Alternatively, the speed of the vehicle may be automatically reduced inaccordance with a distance to the obstruction (another vehicle).

[0051] Then, it is determined whether scanning is completed in alldirections (act 207); if not, the processing goes back to act 203,performs scanning in the next scanning direction, and repeats subsequentsteps.

[0052] The 3-D geographical data may be installed in a vehicle-mounteddevice in advance, or only necessary sections may be provided externallyvia communications.

[0053] It is to be understood that a wide range of changes andmodifications to the embodiments described above will be apparent tothose skilled in the art and are contemplated. It is therefore intendedthat the foregoing detailed description be regarded as illustrative,rather than limiting, and that it be understood that it is the followingclaims, including all equivalents, that are intended to define thespirit and scope of the invention.

What is claimed is:
 1. An apparatus for detecting an object around avehicle comprising: a vehicle positioning device operable to detect avehicle position; a database, the database including three-dimensionalgeographical data; an area defining device operable to utilize thethree-dimensional geographical data to define an area for detecting atarget; object detecting device operable to measure a distance between avehicle position and an object and determine whether the object iswithin the area defined by the area defining unit; and an output deviceoperable to identify if the object detecting device has detected anobject within the area.
 2. The apparatus of claim 1, wherein the areadefining device calculates the area for detecting a target bycalculating a distance between the position of the vehicle and abuilding that is greater than or equal to a predetermined height.
 3. Theapparatus of claim 1, wherein the area defining device calculates thearea for detecting a target to be a detectable distance from the vehicleposition when no building is identified.
 4. The apparatus of claim 1,wherein the object detecting device scans in a 360 degree range.
 5. Theapparatus of claim 1, wherein the object detecting device compares thedistance between the vehicle position and the object with the distancebetween the vehicle position and a building.
 6. The apparatus of claim4, wherein the object detecting device associates a direction with thedistance between the vehicle position and the object.
 7. A method fordetecting an object on a road around a vehicle comprising the acts of:providing a vehicle; providing a database, the database includingthree-dimensional geographical data; calculating a first distance, thefirst distance relating to a position of the vehicle and a first object;utilizing the first distance to define an area for detecting a target;measuring a second distance, the second distance relating to a positionof the vehicle and a second object; determining that the second objectis an obstruction if the second object is in the area for detecting atarget; and outputting an indication that the second object is anobstruction.
 8. The method of claim 7, wherein the first object is abuilding.
 9. The method of claim 7 wherein the building has a height isgreater than or equal to a predetermined height.
 10. The method of claim7 wherein further comprising the act of determining if the firstdistance is greater than the second distance.
 11. The method of claim 7further comprising the act of associating a direction with the firstdistance.
 12. The method of claim 7 further comprising the act ofassociating a direction with the second distance.
 13. An apparatus fordetecting an object on a road around a vehicle comprising: a vehiclepositioning device operable to detect a vehicle position; a geographicaldatabase containing geographical data; a radar device operable to emit aradio beam, receive radio waves reflected from an object, and detect aposition of the object; and an obstruction detecting and controllingdevice operable to gather geographical data from the geographicaldatabase, identify a vehicle position in which the sensitivity of theradar device should be changed, and instruct the radar device to changeits sensitivity.
 14. The apparatus of claim 13, wherein the obstructiondetecting and controlling device is operable to identify a vehicleposition for the resetting of the sensitivity of the radar device andinstruct the radar device to reset the sensitivity to its originallevel.
 15. The apparatus of claim 14, wherein the vehicle position inwhich the sensitivity of the radar device should be changed correspondsto a beginning portion of a section of a road with increased detectablenoise and vehicle position for resetting the sensitivity of the radardevice corresponds to an end portion of the section of the road.
 16. Theapparatus of claim 15, wherein the section of the road is proximate to atunnel, a steel bridge, or a sound barrier.
 17. A method for detectingan object on a road around a vehicle, comprising the acts of: providinga radar device operable to emit a radio beam and receive radio wavesreflected from an object; providing geographical data; identifying afirst location, the first location corresponding to a vehicle positionfor changing the sensitivity of the radar; utilizing the geographicaldata to determine if the vehicle has reached the first location;instructing the radar device to change its sensitivity when the vehiclereaches the first location.
 18. The method for detecting the object ofclaim 17 further comprising the acts of: identifying a second location,the second location corresponding to a vehicle position for resettingthe sensitivity of the radar; utilizing the geographical data todetermine if the vehicle has reached the second location; andinstructing the radar device to reset its sensitivity when the vehiclereaches the second location.